The end of Office Online Server is part of a wider direction of travel from Microsoft: away from self-hosted control and towards Microsoft hosted Office 365.

For some organisations, that may be acceptable. For many, it creates serious questions. Public sector bodies, regulated industries, sovereign cloud providers, managed service providers and anyone else who values privacy and GDPR compliance cannot move document collaboration deeper into Microsoft’s cloud. Indeed, this was why they originally chose MOO on premise.

As well as those with regulatory needs, many organisations are concerned about moving their data and getting further tied into the Microsoft ecosystem.

From 1 January 2027, organisations still using it will be running without security updates, bug fixes or technical support, in an era of increasingly aggressive AI driven cyber-attacks.

Office Online Server is retiring on 31 December 2026. It is the engine behind every in-browser document experience on SharePoint on-premises.

Without a replacement, your users fall back to downloading files and editing on the desktop — losing collaboration your teams rely on every day.

What's retiring?

1. In-browser editing: Word, Excel and PowerPoint files opened and edited directly in the browser.
2. Real-time co-authoring: Multiple people editing the same document at the same time.
3. Previews and viewing: Document previews and read-only viewing across your sites and libraries.

Collabora Online is simple to integrate with your SharePoint Server. There are a few simple settings to make your users benefit of all the advantages of Collabora Online.

Install Collabora Online on a server, then bind SharePoint to it — two commands in the SharePoint Management Shell:

1. Set the WOPI bindings inpowershell with:

New-SPWOPIBinding -ServerName cool-server-name.example.com:port

(replace cool-server-name.example.com with the host name of the Collabora Online server, and port with the port number, that is 9980 by default.

2. Set the WOPI Zone with

Set-SPWOPIZone -Zone "external-https".

Read this blog post for more detailed technical information.